(1) Field of the Invention
The present invention relates to a coin collection/refund circuit and more particularly to a digitally activated coin control circuit for use in combination with a digitally activated ringing circuit for common manipulation by a central processing unit associated with telephone switching center of a prepaid coin station to collect and refund deposited coins.
(2) Description of the Prior Art
Typically, coin control circuitry has been implemented via a collection of analog circuit equipment. With the advent of computer control electronic switching systems, a need arose for simple interfacing between computer controlled and coin controlled circuitry. Usually, elaborate interface connections had to be designed for interfacing the computer controled logic with the logic of the coin control circuit. The logic of computers is digital in nature and of relatively low power, whereas the logic of coin control circuitry is analog in nature. Such analog interface circuits as those mentioned are costly and complex in design.
In order for a telephone switching center to manipulate a prepaid coin telephone station, several different types of circuits had to be connected one at a time to the coin station. For example, initially a coin control circuit was connected to the pay station line to perform coin control manipulations, such as returning coin for a free call number. Once the called number was dialed and the switching center made proper connections to the called subscriber a ringing circuit had to be connected to the line. After completion of the call, the coin control circuit again had to be connected to the line to perform the function of collection of the coin.
One such typical coin detection circuit is shown by U.S. Pat. No. 3,760,112 issued on Sept. 18, 1973 to J. E. Busch.
Therefore, it is the object of the present invention to provide a coin control circuit for use in a computer control telephone central office to digitally interface between the central processing unit of a telephone switching center and a switching network, to provide for common manipulation of ringing signal generation and coin control function for a prepaid coin telephone station.
It is the feature of the present invention to provide the coin control function with the ringing signal generation function so that separate circuits are not required for these functions and so that the computer controller of the telephone central office may make only one connection to the prepaid coin station, thereby minimizing the time required to handle a particular coin station.